31 SPERMATIC PARTICLES. 



Acherson), — which, bj expansion from endosmosis, become holluw vesicles, inside of 

 which are formed nuclei, by a kind of condensation of their granular contents, they then 

 being nucleated cells. This mode of cell-formation, and which, as far as my observa- 

 tion goes, is the mode of cell-genesis in the animal economy, differs, it will be seen, es- 

 sentially from that set forth by Schwann and Schleiden, as to these two points, viz. : — 

 1st. That the nucleus and cell are one and the same as to their histological character ; 

 and 2d. That the cell precedes, as to its formation, its nucleus, instead of the reverse. 



These histological facts are more than interesting, because, as I have stated in an- 

 other place. Professor Agassiz, in his studies of the formation of the ovum, has arrived 

 at the conclusion that the primitive cell, on which the ovum starts, (and this, I have no 

 doubt, is an epithelial cell from the lining membrane of the ovary,) arises in the same 

 manner. And the bearing of this will be the more forcibly seen, as we pass on to show 

 that the formation of Spermatozoa is strictly but a miniature embryology. 



Having thus passed the preliminaries of our subject, concerning which little has 

 hitherto been done, and about which, therefore, little has until now been known, we 

 next come to a section to which the direct processes of the formation of the Spermatozoa 

 belong, and upon which most of the labors in this direction have been spent. That 

 it may appear that I do not ignore what has been done in former times, it will be proper 

 for me to allude briefly to the history of this subject. 



Although this subject has been one in that category which has been pursued since 

 the days oi assisted optics, yet most of what is valuable may be dated only as far back 

 as the early labors of Siebold.* These were soon followed by those, well marked for 

 their elaborate character, of R. Wagner.f 



The researches of Kolliker,! however, since 1840, claim the highest credit, and it is 

 to these that some of our clearest ideas of the " Spermatic Particles " can be traced. 

 Kolliker was the first to break up those rude notions of the animality of these bodies, 

 and, considering them no longer meriting the name of Spermatozoa, he termed them 

 Spermatic Particles. I need not review the wide field over which these men have 

 passed. 



Both Wagner and Kolliker have described and figured the size and form of these 

 bodies in very manv of the genera of the animal kingdom. They have shown that they 



* In MuUer's Archiv, 1836, p. 232. 



+ Fragmente zur Physiologic der Zeugung ; Beitrdge zur Geschichte der Zeugung und Enlwickelung. 

 Munich, 1837. 



I Beitrdge zur Kenntniss der Geschlecht- Verhdhnisse und Samenflussigkeit Wirbelloser Thiere. Berlin, 

 1841. Also, Die Bildung der Samenfalen in Blaschen. Nuremberg, 1846. 



